Honestly, preparing for an accident itself is pretty much the standard stuff...

Buy a car that scores well in crash testing and in the real world accident reports. Not sure if you have disclosure of the stats in the US; in Europe it is available from people like Folksam here: http://www.folksam.se/polopoly_fs/1.11226!/sakrabilar2005.pdf albeit 2005 is the latest year available, in English anyway.

Drive defensively and make sure you have as many of the 'helpers' like ABS, stability control and quality tyres that you can get.